Reconciling late Miocene climate and carbon dioxide levels



The Miocene epoch, about 23–5 million years ago, was warmer than today. However, reconstructions indicate that it also had levels of atmospheric carbon dioxide (CO2) similar to preindustrial values. Scientists have had difficulty reconciling the Miocene temperatures and CO2 levels in models. Knorr et al. ran simulations using a coupled atmosphere-ocean general circulation model to try to simulate a warm late Miocene climate with preindustrial CO2 levels. They analyzed the importance of tectonic factors and vegetation changes driving the late Miocene climate and found that the temperature could largely be explained by the vegetation distribution, thus showing that the warmer late Miocene climate can be reconciled with the preindustrial CO2 concentrations. (Geophysical Research Letters, doi:10.1029/2011GL048873, 2011)